Field of Invention
The present invention relates to a phase-change material and a preparation method thereof, and more particularly to an Sb—Te—Ti phase-change thin-film material applicable to a phase-change memory.
Description of Related Art
Phase-change memory (or Phase Change Random Access Memory, PCRAM for short) use phase change materials, i.e. chalcogenide compounds as storage medium, which may be electrically switched between a generally crystalline state (relatively lower resistance) and a generally amorphous state (relatively higher resistance) by utilizing electric energy (heat) for electronic memory application in order to write and erase information. Information read is relied on the measured resistance, in which whether it is a higher resistance representing “1” or a lower resistance representing “0” is determined.
Grain growth dominates during a crystallization process of Sb—Te based phase-change materials, resulting in a high phase-change rate and a lower melting point than that of Ge2Sb2Te5 (GST). As a result, less power is consumed. However, the Sb—Te based phase-change materials have such disadvantages as a low crystallization temperature, poor thermal stability, and poor data retention.
An Sb2Te3 phase-change material has a very high crystallization rate, and meanwhile a low melting point. However, Sb2Te3 has a very low crystallization temperature, and a very poor thermal stability. For consumer electronics, a non-volatile memory is required to store data for at least 10 years under the condition of 85° C., and even stricter requirements exist in industrial electronics. Without being doped, the Sb2Te3 phase-change material cannot be applied to a phase-change memory.
In the present invention, the Sb2Te3 phase-change material is doped with Ti to significantly rise the crystallization temperature, so as to improve the data retention, thereby satisfying practical requirements.